Healthy Lifestyle and the Likelihood of Becoming a Centenarian

Key Points Question Is a healthy lifestyle associated with a higher likelihood of becoming a centenarian? Findings In this nested case-control study, individuals aged 80 years or older were evaluated, including 1454 centenarians and 3768 individuals who died before reaching 100 years. Individuals with the highest healthy lifestyle score (constructed from smoking, exercise, and dietary diversity) had a significantly higher likelihood of becoming a centenarian, compared with those with the least healthy lifestyle behaviors. Meaning The findings of this study suggest that adhering to a healthy lifestyle could be beneficial even at a very advanced age.


Assessment of individual lifestyle factors
Specifically, the status of smoking (never: 2, former: 1, and current: 0) was determined using two yes-or-no questions: "Do you smoke cigarettes at present?", and "Did you smoke cigarettes in the past?".People who answered yes for the first questions were defined as current smokers regardless of the answer for the second question; people who answered no for the first question but yes for the second question were categorized as former smokers, otherwise as never smokers.Likewise, the status of alcohol use (never: 2, former: 1, and current: 0), and exercise (current: 2, former: 1, and never: 0) were determined similarly by the following questions: "Do you drink alcohol at present?", and "Did you drink alcohol in the past?"."Do you exercise regularly (eg.Running, Qigong, etc.) at present?", and "Did you exercise regularly (eg.Running, Qigong, etc.) in the past?" 1 Dietary intake was evaluated based on a food frequency questionnaire, 2 and dietary diversity was assessed according to the frequency of consuming five food groups: fruits, vegetables, fish, beans, and tea.
Participants reported "almost every day," "except winter or sometimes or occasionally," or "rarely or never."for the intake frequency of each food group, and were assigned scores of 2, 1, or 0 accordingly, 3 generating a total dietary diversity score ranged from 0 to 10.We then classified scores of 7-10 as favorable (2 points), 4-6 as intermediate (1 point), and 0-3 as unfavorable (0 point) for inclusion in the healthy lifestyle score calculation (eTable 1 in the Supplement).Given that height measurements were unavailable in the first four waves of surveys, knee height, measured by trained medical staff during the physical examination, was used to estimate individual height, following two validated equations focused on older Chinese, developed by Zhang et al. (Men: height=67.78+2.01×kneeheight; women: height=74.08+1.81×kneeheight). 4BMI was calculated as measured weight (kg) /estimated height squared (m 2 ), and categorized as underweight (BMI < 18.5 kg/m 2 ), normal (18.5 kg/m 2 ≤ BMI < 24.0 kg/m 2 ), overweight/obese (BMI ≥ 24.0 kg/m 2 ). 5 As underweight has been associated with increased risk of all-cause mortality while overweight was inversely associated with mortality among people ≥ 80 years old in China, 6 we assigned scores of 0, 1, 2 for the underweight, overweight/obese, and normal weight participants.

Redefined drinking status
Alcohol consumption amount was used to redefine drinking status 7,8 , determined by two additional questions: "How much alcohol per day on average do you drink at present, or in the past (if quit drinking)" and "What kind of alcohol do you drink at present, or in the past (if quit drinking)", categorized individuals as heavy (i.e.≥41 g/day for men, and ≥21g/day for women; 0 points), moderate (i.e.>0 and ≤40 g/day for men, and >0 and ≤20g/day for women; 1 point), or none drinkers (0 g/day; 2 points), according to WHO's International guide for monitoring alcohol consumption and related harm 9 .This 3-point scale for alcohol consumption was then incorporated into the HLS-100.

Assessment of physical and cognitive function, and mental wellness
Physical function was assessed using the Activities of Daily Living (ADL) index, with normal physical function defined as not requiring any form of assistance (ranging from partial to complete help) in performing daily tasks such as bathing, dressing, toileting, getting out of bed, and feeding. 10

Cognitive function was evaluated by a validated Chinese version of the Mini-Mental State Exam
(MMSE), with a score ≥18 indicating normal cognitive performance. 11Mental wellness was determined by two questions asking about the feeling of loneliness and anxiety: "How often do you feel lonely or isolated" and "How often do you feel anxious", participants who answered "sometimes", "often", or "always" were classified as "yes" and participants who answered "never" or "seldom" were classified as "no" for each question, and having no feeling of loneliness or anxiety were considered as good mental wellness.

Association between healthy lifestyle and likelihood of becoming centenarians using the binary version HLS-100
We conducted a secondary analysis using the three components as for HLS-100, in which each lifestyle factor was categorized as binary variables, never smoker, current exercisers, and individuals with favorable diet diversity score received 1 point, respectively, otherwise received 0 points, generating a binary version HLS-100 ranging from 0-3 points, then we categorized individuals with 0-1 points as unhealthy lifestyle group, and those with 2-3 points as healthy lifestyle group.With the binary version HLS-100, we re-examined the association between healthy lifestyle and likelihood of becoming centenarians.

Estimation of predictive possibility of becoming centenarians
We developed a predictive model to estimate the possibility of becoming centenarians at individual level based on the aforementioned variables, 12 then computed the group average according to different HLS-100 category and scores of individual healthy lifestyle factors (smoking, exercise, and dietary diversity).

Subgroup analysis
Interactions between HLS-100 and residence, years of education, marital status, chronic conditions, alcohol use status, and BMI were examined with the likelihood ratio test, and subgroup analyses were conducted when significant interaction was observed.

Mediation analysis
We further conducted a mediation analysis using the most recent chronic conditions before the endpoint event (death for controls and living to 100 years for cases) to examine the potential mediation effect of chronic conditions on the association between HLS-100 and the likelihood of  a Adjusted for age (continuous), sex (men and women), entry year (1998, 2000, 2002, 2005, and 2008), residence (urban dwellers, rural dwellers, and missing), duration of education (0, 1-9, > 9 years, and missing), marital status (in marriage, not in marriage, and missing), hypertension (yes, no, and missing), diabetes (yes, no, and missing), cardiovascular disease (CVD) (yes, no, and missing), cancer (yes, no, and missing), alcohol use status (never, former, and current), and body mass index (<18.5kg/m 2 , 18.5-23.9kg/m 2 , and ≥24.0 kg/m 2 )..

eTable 4 .
The predictive probability of the healthy lifestyle score for 100 (HLS-100) and lifestyle components for becoming a centenarian.

The distribution of the number of participants across healthy lifestyle score for 100 (HLS-100).
© 2024 Li Y et al.JAMA Network Open.

Association between healthy lifestyle score for 100 (HLS-100, the binary version) and likelihood of becoming centenarians.
b Reference was the corresponding unfavorable group.eTable 5.
b Not adjusted for alcohol use status (never, former, and current).c© 2024 Li Y et al.JAMA Network Open.eTable 7.

The potential mediation effect of chronic conditions on the association between HLS- 100 and the likelihood of becoming centenarians.
Updated chronic conditions: the most recent chronic conditions before the endpoint event (death for controls and living to 100 years for cases).Adjusted for age (continuous), sex (men and women), entry year(1998, 2000, 2002, 2005, and 2008), residence (urban dwellers, rural dwellers, and missing), duration of education (0, 1-9, > 9 years, and missing), marital status (in marriage, not in marriage, and missing), hypertension (yes, no, and missing), diabetes (yes, no, and missing), cardiovascular disease (CVD) (yes, no, and missing), cancer (yes, no, and missing), alcohol use status (never, former, and current), and body mass index (<18.5kg/m 2 , 18.5-23.9kg/m 2 , and ≥24.0 kg/m 2 ).